1. Field of the Invention
The present invention relates to a method and apparatus for setting configurations of an uplink transport channel in a wireless communications system, and more particularly, to a method and apparatus for a user equipment of a wireless communications system properly setting configurations of an uplink transport channel to enhance system performance.
2. Description of the Prior Art
The third generation (3G) mobile telecommunications system has adopted a Wideband Code Division Multiple Access (WCDMA) wireless air interface access method for a cellular network. WCDMA provides high frequency spectrum utilization, universal coverage, and high quality, high-speed multimedia data transmission. The WCDMA method also meets all kinds of QoS requirements simultaneously, providing diverse, flexible, two-way transmission services and better communication quality to reduce transmission interruption rates. Through the 3G mobile telecommunications system, a user can utilize a wireless communications device, such as a mobile phone, to realize real-time video communications, conference calls, real-time games, online music broadcasts, and email sending/receiving. However, these functions rely on fast, instantaneous transmission. Thus, targeting third generation mobile telecommunication technology, the prior art provides High Speed Downlink Package Access (HSDPA) and High Speed Uplink Package Access (HSUPA), which are used to increase bandwidth utility rate and package data processing efficiency to improve uplink/downlink transmission rate.
HSUPA increases upstream network performance, reduces transmission delay by rapid retransmission of erroneous data transmissions, and can adjust transmission rate based on channel quality. To realize this type of “power control,” HSUPA adopts technologies such as NodeB Scheduling, Hybrid Automatic Repeat Request (HARQ), Soft Handover, and Short Frame Transmission. Correspondingly, the 3rd Generation Partnership Project (3GPP) defines an Enhanced Dedicated Transport Channel (E-DCH) for controlling operations of HSUPA. E-DCH introduces new physical layer channels, such as E-HICH, E-RGCH, E-AGCH, E-DPCCH, and E-DPDCH, which are used for transmitting HARQ ACK/NACK, Uplink Scheduling Information (SI), Control Plane information, and User Plane information. Detailed definitions of the above can be found in the Medium Access Control (MAC) protocol specification, and are not given here.
In HSUPA, a network, e.g. UMTS Terrestrial Radio Access Network (UTRAN), can configure transmit time interval (TTI) and HARQ info of an E-DCH for a user equipment (UE) through an information element (IE) named Added or Reconfigured UL TrCH information. Additionally, at the same time, the network can also add one or several MAC-d flows to the E-DCH or reset configurations of the MAC-d flows carried on the E-DCH through an IE “Added or Reconfigured E-DCH MAC-d flow list” included in the above IE. The operations when the UE receives the IE “Added or Reconfigured UL TrCH information” are briefly introduced in the following.
When the UE receives the IE “Added or Reconfigured UL TrCH information”, the UE can configure the TTI and the HARQ info of the E-DCH according to content of the IE if an uplink transport channel of the UE is set to be E-DCH and there are more than one MAC-d flows carried on the E-DCH. Next, if the IE “Added or Reconfigured UL TrCH information” further includes the IE “Added or Reconfigured E-DCH MAC-d flow list”, the UE can reconfigure the MAC-d flows carried on the E-DCH or add one or several MAC-d flows to the E-DCH according to the IE “Added or Reconfigured E-DCH MAC-d flow list”.
As mentioned above, in the prior art, the IE “Added or Reconfigured UL TrCH information” for E-DCH configuration is allowed only if there is more than one MAC-d flow carried on E-DCH. Thus, if there is only one MAC-d flow carried on E-DCH, the UE cannot change TTI and HARQ info of the EDCH according to the received IE “Added or Reconfigured UL TrCH information”. However, this is the only way to change TTI and HARQ Info for E-DCH. Furthermore, in this case, the only one MAC-d flow carried on the E-DCH cannot be reconfigured as well.